Process of obtaining potassium and other alkali-metal compounds



UNITED STATES PATENT OFFICE.

ERIC HJAL-MAR WESTLING, OF ANTIOCH, CALIFORNIA.

PROCESS OF OBTAINING POTASSIUM AND OTHER ALKALI-METAL COMPOUNDS.

No Drawing.

To alZ whom: it may concern:

Be it known that I, Eiuc HJALMAR WVnsr- LING, a citizen of the United States, and a resident of Antioch. county of Contra Costa, and. State of California. have invented a certain new and useful Process of Obtaining Potassium and other Soluble Alkali- Metal Compounds, of which the following is a specification,

The invention relates to a process of separating potassium and other alkali metals in the form of water soluble compounds from insoluble alkali metal silicates.

An object of the invention is to provide a process of converting the alkali metal in insoluble alkali silicates to a water soluble alkali metal compound.

Another object of the invention. is to provide a process of producing substantially pure alkali metal sulfates from. insoluble alkali metal silicates.

The invention possesses other advantageous features. some of which. with the foregoing, will be set forth at length in the follmving description where I shall mitline in full the preferred method of carrying out the process of my inventiim. In such dcscription I shall describe the process in con-- nection with the recovery of soluble potas 1 sium compounds, but it is to be understood that the process is applicable to other alkali metal and is not limited to potassium.

The process of my invention is particularly applicable to the recovery of water soluble alkali metal compound form. from insoluble anhydrous alkali metal silicates and I will so describe it herein. I have found that by heating a mixture of a heavy metal sulfate and an anhydrous alkali metal silicate to certain tempe'atures under certain conditions, that a reaction occurs in which soluble alkali metal sulfate is formed. Takinp ordinary potash feldspar as the an hydrous alkali metal silicate and ferric sulfate as the heavy metal sulfate, as an illustration, the reaction is essentially as follows:

The heavy metal sulfate is preferabl ferric or aluminum sulfate, but ferrous su fate, copper, ,zinc or lead sulfates may be employed and will act in a similar manner, but probably not as efficiently. The heavy metal sulfate employed should have a high Specification of Lettcrs Patent. lfll'fil1tQ-{l A oy L 1920 Application fil ed October 14, 1918. Serial No. 258.025.

decomposition temperature, so that it will not be broken down before the desired temperature for reaction is reached. Diil'crcnt anhydrous silicates require different tcmpcratures for the best results, but i have, found that in every case about 550 C. is the maximum temperature, since above that temperature the reigerse reaction will occur due to the greater stability of silicates as compared to sulfates at high temperature. A high temperature however is required to decompose the ferric or aluminum sulfate but a working margin of more than 10H" C. exists. since the reaction occurs between 430 and 550 (I in the case of potash feldspar and between lUl) t. and 500" in the case of lepidolite.

Ordinarily ferric or aluminum sulfate will not decompose at a temperature as low as 400 C. but I have found that in the presence of an alkali metal silicate this deco1n position takes place readily at this temperarure.

The reaction is probably due to the activity of sulfuric acid at the high temperatures prcvailii'igr, the acid being in a condi tion ery similar to the nascent state in the case of atoms. Sulfuric acid at a temperature near to but below red heat will decompose most silicates, but the difliculty of maintaining such a coi'idition Without pressure and with attendant vessel material difficulties has made it technically impossible to utilize this property of sulfuric acid. When a heavy metal sulfate-with high decomposition temperature is used, however, this difiiculty disappears. as the newly released acid acts continuously on the silicate, thus producing a continuous reaction, Without presenting at any time a large amount of free acid. The presence of-water vapor facilitates the reaction, but it is not essential In practice, I prefer to evaporate a ferric or an aluminum sulfate solution to the consistency of a thick syrup and then mix the finely ground alkali metal silicate into the hot syrupy mass and then discharge the mixture onto a cooling plate of suitable metal, such as iron or copper and allow the mixture to cool and set into a cake. This cake is later placed in a rotary heater where the proper temperature is maintained by interior or exterior heating or both. The lumps of undecomposed cake act as a stirring agency in the rotar furnace and when all of the lumps are disintegrated the reaction will be as nearly complete {1% is tvclu nicully possible. A rotary durnzurv such us is used in the nmnufactut'e of ceu'mut is excellent for this purpose. The mass is Ilia charged from the fumzu-o, mull-i l, mill lmvlioil with Water after Wl'iinh the bifillltlfll] is bPjHLl'ilU-rll l'i'uni the insoluble l'CSiLllu. lily ducziutntiuru liltmii'ig ui utlurrwisu. Tlu: ulkzili mom]. sulfate solution, is then treated arcm-ilii'zg lo slmulm-ll I'IiPlIlHHlI- for eventual. utilization in he arts 3 vluim l. 'llw {u'nvess 01' nhlnining SUllll l8 alkali l'nfiiill :rmrepmmds from zmliyllmus alkali uwlul muluiuiug sulmtum-vs wliii-li lrui'uprisus limiting: :i mixture of Hie sulwitzinw and a heavy metal sulfide tn 1 liun' uu'alnii'e will ciently iiipjll tn decompose the sulfate in the presence of the substance.

2. The prowess of ulituining alkali lfitl'i'll sulfuhs from anhydrous alkali metal 0F- tiiiningx u'ulislizznm-s uliiirl: mi'uprisw: limiting a mixture ml the sulislzmve and a heavy Il'akf'liil :illlfill'u in Al innpeswil 1m: ubuw WHY {I 3 The lFifi Fh-H ol (-l' l'uil Hg r'll li imu sulfuiw; 51mm iusululillr ilqx flrozus alkali siliwtvs wliivli- (.UUllH'lH-ks heating a mixture of finely divided alliz li. metal iliuute and a heavy metal sulfate to :lemmpose the heavy metal sulfate and form alkali metal sulfate.

4. The process of nbtulning alkali metal sulfate from insoluble ZIHlEFLlFOH-S flllfilli metal silicates which comprises healing a mixture (If alkali. metal silivateand ferric sull'utu in it tmi'i iamture sulliiricutly high to ilecompuse the ferric sulfide.

5. The mm-w u'l obtaining alkali metal sulfate from insoluble :illuili nuruil Hllllfiilt ,s \Vlll('ll mnsiqls; in mixing; finely (livillml sili mile uml u tliil-l; snluliuzi of a liemy i'nrglilil sulfate, allowing the mass tn set and l'urn; =1 sake null llfiill lug the cake in u teniigienilurc ulii :-i-ull;v liigli 11) cause the, fm-muiicm ulf :1ll:.ili n'mtul sulfate.

6. The pi'uciw n'l' whmiuing :iillml nmtal rllllldtfl l'mm lllrifllll lle :illmli uwtul siluulu, \Vlllfll irnusirsl s in mixing incl divided ill (rate zuul u limit-l; Qullllluil ml it lucnvy metal sulfide, 21llf)ll2' f the mass in wt null form :1 calm, agitating; illhl lwullu; flu; calm tn ('uuse lemmpimiliiuii m tliu lwu'v y lll -l'.- ll Hill fate and the f=',-1'=muliii r1 of alkali UlQlgll sul' fate, and sepminling lllifi illliill mfizal sulfa i'rom the I'Hzltlkll n'mew'.

l 11 tLStlll'lUllIY whereof l have bas l-unto 545i my hand at San Francisco, California, this 7th clay of ()vtober 1918.

In. presel'ice oi 

